Two mode thermostat with set-back temperature and humidity set-point feature

ABSTRACT

Various thermostat embodiment are provided that includes at least a first sensor configured to communicate information indicative of the temperature within the space, and at least a second sensor configured to communicate information indicative of the humidity within the space. The thermostat further includes a controller in communication with the at least first and second sensors, for controlling the thermostat&#39;s operation. The controller is configured to operate in a first mode in which the controller operates the air conditioner when the sensed temperature of the space is above a temperature set-point or when the sensed humidity level is above the humidity set-point. The controller is further configured to operate in a second mode in which the controller operates the air conditioner when the sensed temperature is below a set-back temperature set-point, or when the sensed humidity is above a set-back humidity set-point.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/870,355, entitled “Two Mode Thermostat with Set-Back Temperature andHumidity Set-Point Feature Field”, filed Aug. 27, 2010, which is adivisional of U.S. patent application Ser. No. 11/796,923, filed Apr.30, 2007, now U.S. Pat. No. 7,793,510, issued Sep. 14, 2010. The entiredisclosures of the above applications are incorporated herein byreference.

FIELD

The present disclosure relates to thermostats, and in particular, tothermostats used for controlling humidity levels within a conditionedspace.

BACKGROUND

Thermostats are used to control climate control systems to maintain thetemperature in a space conditioned by the climate control system. Thetypical thermostat compares the sensed temperature of the space with aset point temperature and activates the climate control system to heator cool the space to the desired set point temperature. Some climatecontrol systems further control conditioning to the space to provideeither humidification or dehumidification control. In such systems, thethermostat is capable of sensing a space temperature that is above thedesired temperature set-point, and responsively controlling operation ofthe air conditioner to cool the space to the temperature set-point. Thethermostat is also capable of sensing a humidity level that is above thedesired humidity set-point, and responsively controlling operation ofthe air conditioner to dehumidify the space to the humidity set-point.Such a thermostat will operate the air conditioner to lower the humiditylevel in the space below the humidity set point, even when the sensedtemperature is already below the temperature set point. This results inthe space being cooled below the desired temperature set point until thedesired humidity level is attained. However, this can cause unwantedenergy consumption in situations where it is not desired to furtherlower the temperature of the space.

SUMMARY

The present disclosure relates to thermostats that control a climatecontrol system to provide for cooling a space and also dehumidifying thespace. In one aspect of the present disclosure, various embodiments of athermostat for controlling the operation of at least an air conditionerfor conditioning a space are disclosed. The various embodiments compriseat least a first sensor configured to communicate information indicativeof the temperature within the space, and at least a second sensorconfigured to communicate information indicative of the humidity withinthe space. The thermostat further comprises a controller incommunication with the at least first and second sensors, forcontrolling the thermostat's operation. The controller is configured tooperate in a first mode in which the controller operates the airconditioner when the sensed temperature of the space is above atemperature set-point or when the sensed humidity level is above thehumidity set-point. The controller is further configured to operate in asecond mode in which the controller only operates the air conditionerwhen the sensed temperature is above a set-back temperature set-point,or when the sensed humidity is above a set-back humidity set-point.

In another aspect of the present disclosure, a method for controllingthe operation of the various thermostat embodiments is further provided.The method comprises sensing the temperature of the space to bemaintained, sensing the humidity level of the space to be maintained,determining if the sensed humidity level is above the desired humidityset point, determining if the sensed temperature is above thetemperature set point but less than a predetermined amount above thetemperature set point, and responsively establishing operation of thecompressor. The method calls for establishing operation of thecompressor at full capacity and the blower at less than full capacitywhen the sensed humidity is above the desired humidity set point, andwhen the sensed temperature is above the temperature set point but lessthan a predetermined amount above the temperature set point.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a side elevation view of a particular climate control systemfor a space having a thermostat according to the principles of thepresent disclosure;

FIG. 2 is a flow-chart illustrating one embodiment of a thermostat andmethod for controlling a thermostat according to the principles of thepresent disclosure;

FIG. 3 is a flow-chart illustrating a second embodiment of a thermostatand method for controlling a thermostat according to the principles ofthe present disclosure;

FIG. 4 is a side elevation view of a multi-stage climate control systemfor a space having a thermostat according to the principles of thepresent disclosure;

FIG. 5 is a flow-chart illustrating another embodiment of a thermostatand method for controlling a thermostat according to the principles ofthe present disclosure;

FIG. 6 is a flow-chart illustrating yet another embodiment of athermostat and method for controlling a thermostat according to theprinciples of the present disclosure; and

FIG. 7 is a flow-chart illustrating yet another embodiment of athermostat and method for controlling a thermostat according to theprinciples of the present disclosure.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses. Itshould be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.

According to various aspects of the present disclosure, there areprovided various exemplary embodiments of a thermostat for maintaining adesired temperature and humidity setting for a space. In the variousthermostat embodiments, a thermostat is provided that is programmable toinclude at least two temperature set-points corresponding to at leasttwo different time periods during the day, at least one period of whichis a set-back period during which the space is to be unoccupied andclimate control operation is curtailed. The various embodiments compriseat least a first sensor configured to communicate information indicativeof the temperature within the space, and at least a second sensorconfigured to communicate information indicative of the humidity levelwithin the space. The thermostat further comprises a controller incommunication with the at least first and second sensors, forcontrolling the thermostat's operation. The controller is configured tooperate in a first mode in which the controller operates the airconditioner when the sensed temperature of the space is above atemperature set-point, or when the sensed humidity level is above thehumidity set-point. The controller is further configured to operate in asecond mode in which the controller only operates the air conditionerwhen the sensed temperature is above a set-back temperature set-point,or when the sensed humidity is above a set-back humidity set-point.

One example embodiment of a method for controlling the operation of athermostat for an air conditioner is shown in FIG. 7. The airconditioner includes a variable speed compressor and blower, a humiditysensor and a temperature sensor. A step 700 includes sensing thetemperature and humidity of a space to be maintained. A step 704includes determining if the sensed humidity level is above the desiredhumidity set point. A step 708 includes determining if the sensedtemperature is above the temperature set point but less than apredetermined amount above the temperature set point. If yes, then instep 712, operation of the compressor is established at full capacityand the blower at less than full capacity, i.e., when the sensedhumidity is above the desired humidity set point and when the sensedtemperature is above the temperature set point but less than apredetermined amount above the temperature set point. Additionally oralternatively, in some embodiments the controller may establishoperation of the compressor at full capacity and operation of the blowerat full capacity when the sensed temperature rises more than thepredetermined amount above the desired temperature set point. In someembodiments the controller may responsively establish operation of thecompressor at full capacity and operation of the blower at full capacitywhen the sensed humidity is below the desired humidity set point, andthe sensed temperature is within a predetermined amount above thedesired temperature set point.

In one first embodiment shown in FIG. 1, a programmable thermostat 100is provided that is preferably in communication with various componentsof a climate control system 20. The climate control system 20 includesan air conditioning system having a compressor unit 22 and a blower unit24, which may be operable in at least two speeds. The thermostat 100controls the operation of the air conditioning system via connections toa compressor motor and a blower motor (not shown). The thermostat 100 isprogrammable to include at least two temperature set-pointscorresponding to at least two different time periods during the day, atleast one period of which is a set-back period during which the space isto be unoccupied and climate control operation is curtailed. In anexample of such a set-back period, the thermostat may switch from adesired 72 degree set point temperature to a set-back temperatureset-point of 80 degrees when the space is un-occupied, to thereby reduceair conditioning operation during the set-back time period. Thethermostat 100 further comprises an internal or external temperaturesensor 126, and an internal or external humidity sensor 128, whichsensors allow for determination of the temperature and humidity withinthe space.

In the first embodiment of a thermostat, the thermostat includes atleast one temperature responsive device 126 that at least periodicallyoutputs a variable or value that is indicative of the temperature in thespace. The sensor may be any of a number of sensor types, and maycomprise a crystal, oscillator or other electronic component having afrequency that responsively changes with temperature. Alternatively, thesensor may comprise a thermistor having a resistance value that changesin response to changes in temperature. The sensor could also be a devicecapable of communicating a voltage value that correlates to, or isindicative of, the temperature sensed in the space. The sensor mayinclude circuitry to permit the sensor to communicate an absolute valueof the temperature to a tenth of degree Fahrenheit. Likewise, the sensormay also include circuitry to enable communication of temperatureinformation on a periodic basis, or upon request, such as when promptedby a microprocessor of the thermostat. Accordingly, the at least onesensor in the various embodiments is configured to sense and communicateinformation that is indicative of the temperature in the space.

In the first embodiment of a thermostat, the thermostat 100 furtherincludes at least a second sensor or humidity responsive device 128 thatat least periodically outputs a variable or value that is indicative ofthe humidity level in the space. The second sensor may be any of anumber of sensor types, and may comprise a crystal, oscillator or otherelectronic component having a frequency that responsively changes withhumidity. Alternatively, the second sensor may comprise a thermistorhaving a resistance value that changes in response to changes inhumidity level. The second sensor could also be a device capable ofcommunicating a voltage value that correlates to, or is indicative of,the sensed humidity level in the space. The second sensor may includecircuitry to permit the sensor to communicate an absolute value of thehumidity level. Likewise, the second sensor may also include circuitryto enable communication of sensed humidity level information on aperiodic basis, or upon request, such as when prompted by amicroprocessor of the thermostat 100. Accordingly, the at least onesecond sensor in the various embodiments is configured to sense andcommunicate information that is indicative of the humidity level in thespace.

In the first embodiment, the thermostat 100 comprises a controller ormicroprocessor (not shown) for receiving communication signals from theat least one temperature sensor and at least one humidity sensor. Thethermostat 100 is also configured to enable an occupant to provide inputto the processor of a desired temperature set point and a desiredhumidity set point. The controller or microprocessor in the firstembodiment is preferably a SCC825A microcontroller manufactured bySamsung, which includes a software program for controlling the operationof the thermostat 100 in at least a first mode of operation and a secondset-back mode of operation.

In the first embodiment's first mode of operation, the controllerinitiates signals for controlling the activation of the air conditionersystem in response to a communication or signal from the at least onetemperature sensor indicating that the space temperature is above aprogrammed temperature set point for a programmed time period in whichthe space is to be occupied (a non-set-back time period). Specifically,the program in the microprocessor operates according to the flow chartshown in FIG. 2. At step 200 and 202 the microprocessor receivescommunication indicating the value of the sensed temperature T and thesensed humidity level H, which are then stored. The microprocessor alsomonitors whether the end of the time period in which the set pointtemperature is to be maintained at step 204. At step 210, themicroprocessor then compares the sensed temperature to the programmedtemperature set point (72° F., for example), and compares the sensedhumidity to the desired humidity set point (50%, for example). If thesensed temperature is greater than the set point temperature, but thesensed humidity level is below the humidity set point, the processorinitiates signals at step 220 for activating relays to operate the airconditioner as needed until the sensed temperature is lowered toapproximately the temperature set-point value. This operates the airconditioner to primarily cool the space. If the sensed temperature isgreater than the set point temperature, regardless of whether the sensedhumidity level is above the humidity set point, the microprocessorinitiates signals at step 220 for activating relays to operate the airconditioner as needed until both the sensed temperature is lowered tothe temperature set-point value, and the sensed humidity level islowered to the humidity set-point value. It should be noted that at step220, the thermostat may operate the blower unit at a reduced speed, suchthat the circulating air has more time for heat transfer to therebyremove more moisture from the air. This operates the air conditioner toboth cool and dehumidify the space. If the sensed temperature is belowthe set point temperature, but the sensed humidity level is above thehumidity set point at step 230, the microprocessor initiates signals atstep 220 for activating relays to operate the air conditioner as neededuntil the sensed humidity level is lowered to the humidity set-pointvalue. It should be noted that in step 220, the thermostat may operatethe blower unit at a reduced speed, such that the circulating air hasmore time for heat transfer to thereby remove more moisture from theair. This operates the air conditioner to primarily dehumidify thespace, and may result in cooling the space to a temperature below thetemperature set-point.

In the first embodiment's second mode of operation, the controllerinitiates signals for controlling the activation of the air conditionersystem in response to a communication or signal from the at least onetemperature sensor, indicating that the space temperature is above aprogrammed set-back temperature set point for a programmed time periodin which the space is to be unoccupied (a set-back time period).Specifically, the program in the microprocessor operates according tothe flow chart shown in FIG. 3. At step 300 and 302 the microprocessorreceives communication indicating the value of the sensed temperature Tand the sensed humidity level H, which are then stored. At step 310, themicroprocessor then compares the sensed temperature to the programmedset-back temperature set point (80° F., for example), and compares thesensed humidity to the programmed set-back humidity set point (65%, forexample). If the sensed temperature is greater than the programmedset-back temperature set point, but the sensed humidity level is belowthe programmed set-back humidity set point, the processor initiatessignals at step 320 for activating relays to operate the air conditioneras needed until the sensed temperature is lowered to approximately theset-back temperature set-point. This reduces the extent of airconditioner operation in maintaining an elevated “set-back” temperaturesetting, which reduces energy consumption relative to the standardtemperature set-point value. It should be noted that the set-backhumidity set-point is essential to attaining this reduced operation,since the sensed humidity level could easily rise above the desired“standard” humidity set-point and trigger a demand for air conditioningoperation.

If the sensed temperature is greater than the programmed set-backtemperature set point, regardless of whether the sensed humidity levelis above the programmed set-back humidity set point, the microprocessorinitiates signals at step 320 for activating relays to operate the airconditioner as needed until both the sensed temperature is lowered tothe set-back temperature set-point, and the sensed humidity level islowered to the programmed set-back humidity set-point. It should benoted that in step 320, the thermostat preferably operates the blowerunit at its maximum speed or capacity, such that the space is cooled ata greater rate to thereby shorten the time it takes the air conditionerto reach the set-back temperature setting. This operates the airconditioner at a reduced level to lower the temperature and humiditytowards the “set-back” temperature and “set-back” humidity settings,which also reduces energy consumption over the standard programmedtemperature and humidity set-point values.

If the sensed temperature is below the programmed set-back temperatureset point, but the sensed humidity level is above the programmedset-back humidity set point at step 330, the microprocessor initiatessignals at step 320 for activating relays to operate the air conditioneras needed until the sensed humidity level is lowered to the programmedset-back humidity set-point value. This operates the air conditioner ata reduced level to dehumidify the space to an elevated “set-back”humidity setting, which reduces energy consumption over the standardhumidity set-point value. Alternatively, the thermostat may beconfigured to ignore the sensed humidity level during a set-back period,such that the air conditioner is operated only for the purpose ofmaintaining the set-back temperature set-point at step 320. In eitherconfiguration, the thermostat is configured to avoid operation of theair conditioner in maintaining the desired humidity set-point during aset-back period, such that a reduction in operation is achieved from ahigher set-back temperature set-point (without the sensed humiditytriggering unnecessary air conditioning operation).

In a second embodiment shown in FIG. 4, a programmable thermostat 400 isprovided that is preferably in communication with various components ofa climate control system 20. The climate control system 20 includes anair conditioning system having a compressor unit 22 and a blower unit24, each of which is capable of operating at both a full capacity leveland a less than full capacity level. The thermostat 400 controls theoperation of the air conditioning system via connections to a compressormotor and a blower motor. The thermostat 400 is programmable to includeat least two temperature set-points corresponding to at least twodifferent time periods during the day, at least one period of which is aset-back period during which the space is to be unoccupied and climatecontrol operation is curtailed. In an example of such a set-back period,the thermostat may switch from a desired 72 degree set point temperatureto a set-back temperature set-point of 80 degrees when the space isun-occupied, to thereby reduce air conditioning operation during theset-back time period. The thermostat 400 further comprises an internalor external temperature sensor 426, and an internal or external humiditysensor 428, which sensors allow for determination of the temperature andhumidity within the space.

In the second embodiment of a thermostat, the thermostat 400 includes atleast one temperature responsive device 426 that at least periodicallyoutputs a variable or value that is indicative of the temperature in thespace. The sensor may be any of a number of sensor types, and maycomprise a crystal, oscillator or other electronic component having afrequency that responsively changes with temperature. Alternatively, thesensor may comprise a thermistor having a resistance value that changesin response to changes in temperature. The sensor could also be a devicecapable of communicating a voltage value that correlates to, or isindicative of, the temperature sensed in the space. The sensor mayinclude circuitry to permit the sensor to communicate an absolute valueof the temperature to a tenth of degree Fahrenheit. Likewise, the sensormay also include circuitry to enable communication of temperatureinformation on a periodic basis, or upon request, such as when promptedby a microprocessor of the thermostat. Accordingly, the at least onesensor in the various embodiments is configured to sense and communicateinformation that is indicative of the temperature in the space.

In the second embodiment of a thermostat, the thermostat 400 furtherincludes at least a second sensor or humidity responsive device 428 thatat least periodically outputs a variable or value that is indicative ofthe humidity level in the space. The second sensor may be any of anumber of sensor types, and may comprise a crystal, oscillator or otherelectronic component having a frequency that responsively changes withhumidity. Alternatively, the second sensor may comprise a thermistorhaving a resistance value that changes in response to changes inhumidity level. The second sensor could also be a device capable ofcommunicating a voltage value that correlates to, or is indicative of,the sensed humidity level in the space. The second sensor may includecircuitry to permit the sensor to communicate an absolute value of thehumidity level. Likewise, the second sensor may also include circuitryto enable communication of sensed humidity level information on aperiodic basis, or upon request, such as when prompted by amicroprocessor of the thermostat. Accordingly, the at least one secondsensor in the various embodiments is configured to sense and communicateinformation that is indicative of the humidity level in the space.

In the second embodiment, the thermostat 400 comprises a controller ormicroprocessor for receiving communication signals from the at least onetemperature sensor and at least one humidity sensor. The thermostat 400is also configured to enable an occupant to provide input to theprocessor of a desired temperature set point and a desired humidity setpoint. The controller or microprocessor in the first embodiment may be aSCC825A microcontroller manufactured by Samsung, for example, which isincluded with a software program for controlling the operation of thethermostat 400 in at least a first mode of operation and a secondset-back mode of operation.

In the second embodiment's first mode of operation, the controllerinitiates signals for controlling the activation of the air conditioningsystem in response to a communication from the at least one temperaturesensor indicating that the space temperature is above a programmedtemperature set point for a time period in which the space is to beoccupied (a non-set-back time period. Specifically, the program in themicroprocessor operates according to the flow chart shown in FIG. 5. Atstep 500 and 502, the microprocessor receives communication indicatingthe value of the sensed temperature T and the sensed humidity level H,which are then stored. At step 510, the microprocessor then compares thesensed temperature to the programmed temperature set point (72° F., forexample), and compares the sensed humidity to the desired humidity setpoint (50%, for example). If the sensed temperature is greater than theset point temperature, but the sensed humidity level is below thehumidity set point, the processor initiates signals at step 520 foractivating relays to operate the compressor and blower at full capacityuntil the sensed temperature is lowered to approximately the temperatureset-point value. This operates the air conditioner in a maximum coolingcapacity to quickly cool the space. It should be noted that themicroprocessor/program may be configured, where the sensed temperatureis greater than the set point temperature and the sensed humidity levelis above the humidity set point, to activate relays at step 520 or 540to operate the compressor and blower as needed to lower the temperatureand the humidity towards the temperature set-point value and thehumidity set-point value. It should be noted that in step 540, thethermostat may operate the blower unit at a reduced speed, such that thecirculating air has more time for heat transfer to thereby remove moremoisture from the air. If the sensed temperature is below the set pointtemperature, but the sensed humidity level is above the humidity setpoint at step 530, the microprocessor initiates signals at step 540 foractivating relays to operate both the compressor and blower at less thanfull capacity until the sensed humidity level is lowered to the humidityset-point value. It should be noted that operating the compressor andthe blower unit at a reduced speed gives circulating air more time forheat transfer to thereby remove more moisture from the air, whileminimizing the overall cooling rate to the space. This operates the airconditioner to primarily dehumidify the space, and may result in coolingthe space to a temperature below the temperature set-point.

In the second embodiment's second mode of operation, the controllerinitiates signals for controlling the activation of the compressor andblower of the air conditioning system in response to a communicationfrom the at least one temperature sensor, indicating that the spacetemperature is above a programmed set-back temperature set point for atime period in which the space is to be unoccupied (a set-back timeperiod). Specifically, the program in the microprocessor operatesaccording to the flow chart shown in FIG. 6. At step 600 themicroprocessor receives communication indicating the value of the sensedtemperature T and the sensed humidity level H, which are then stored. Atstep 610, the microprocessor then compares the sensed temperature to theprogrammed set-back temperature set point (80° F., for example), andcompares the sensed humidity to the programmed set-back humidity setpoint (65%, for example). If the sensed temperature is greater than theprogrammed set-back temperature set point, but the sensed humidity levelis below the programmed set-back humidity set point, the processorinitiates signals at step 620 for activating relays to operate thecompressor and blower unit at full capacity until the sensed temperatureis lowered to approximately the set-back temperature set-point. Thismaximum cooling capacity operation reduces the extent of air conditionerrun time in maintaining an elevated “set-back” temperature setting,which reduces energy consumption relative to the standard temperatureset-point value. It should be noted that the set-back humidity set-pointis essential to attaining this reduced operation, since the sensedhumidity level could easily rise above the desired “standard” humidityset-point and trigger a demand for air conditioning operation.

If the sensed temperature is greater than the programmed set-backtemperature set point, regardless of whether the sensed humidity levelis above the programmed set-back humidity set point, the microprocessorinitiates signals at step 620 for activating relays to operate thecompressor and blower unit as needed until both the sensed temperatureis lowered to the set-back temperature set-point, and the sensedhumidity level is lowered to the programmed set-back humidity set-point.It should be noted that the thermostat could also be configured tooperate the air conditioner as in step 620, where the thermostat mayoperate the compressor and the blower unit at its maximum speed orcapacity, such that the space is cooled at a greater rate to therebyshorten the time it takes the air conditioner to reach the set-backtemperature setting. This operates the air conditioner in a manner thatreduces run time in maintaining elevated “set-back” temperature and“set-back” humidity settings, which thereby reduces energy consumptionover the standard programmed temperature and humidity set-point values.

If the sensed temperature is below the programmed set-back temperatureset point, but the sensed humidity level is above the programmedset-back humidity set point at step 630, the microprocessor initiatessignals at step 640 for activating relays to operate the air conditioneras needed until the sensed humidity level is lowered to the programmedset-back humidity set-point value. This operates the air conditioner ata reduced level to dehumidify the space to an elevated “set-back”humidity setting, which reduces energy consumption over the standardhumidity set-point value. Alternatively, the thermostat may beconfigured to ignore the sensed humidity level during a set-back period,such that the air conditioner is operated as in step 620 only for thepurpose of maintaining the set-back temperature set-point. Thisconfiguration may be simply attained by setting the set-back humidityset-point to 100%, for example, such that the sensed humidity will neverbe above the set-back humidity set point. In either configuration, thethermostat is configured to avoid operation of the air conditioner inmaintaining the desired humidity set-point during a set-back period,such that a reduction in operation is achieved from a higher set-backtemperature set-point (without the sensed humidity triggeringunnecessary air conditioning operation).

Thus, the various thermostat embodiments can automatically switchbetween a first mode of operation and a second set-back mode ofoperation, to prioritize reduction in air conditioning operation overmaintaining humidity control to provide optimum energy savings to theoccupant. The advantages of the above described embodiments andimprovements should be readily apparent to one skilled in the art, as toenabling a thermostat with humidity control. Additional designconsiderations may be incorporated without departing from the spirit andscope of the invention. The description in this disclosure is merelyexemplary in nature and, thus, variations are not to be regarded as adeparture from the spirit and scope of the disclosure. Moreparticularly, the apparatus may be adapted to any apparatus for coolinga space. Accordingly, it is not intended that the invention be limitedby the particular embodiments or forms described above, but by theappended claims.

What is claimed is:
 1. A method for controlling operation of a thermostat for an air conditioner having a variable speed compressor and a blower, a humidity sensor and a temperature sensor, the method performed by a controller using input from the sensors to control humidity and temperature of a space, the method comprising the steps of: based on a current time period, the controller using one of a plurality of programmed temperature set points as a desired temperature set point and using one of a plurality of programmed humidity set points as a desired humidity set point; the controller receiving a sensed temperature of the space; the controller receiving a sensed humidity of the space; the controller comparing the sensed humidity with the desired humidity set point; the controller comparing the sensed temperature with the desired temperature set point; and based on the current time period, the controller establishing: (a) a first mode of operation for a non-set-back time period in which the compressor operates at full capacity and the blower operates at less than full capacity when the sensed humidity is above the desired humidity set point and the sensed temperature is within a predetermined amount above the desired temperature set point, or in which the compressor operates at less than full capacity and the blower operates at less than full capacity when the sensed humidity is above the desired humidity set point and the sensed temperature is below the desired temperature set point; and (b) a set-back mode of operation for a set-back time period, in which the air conditioner operates only when the sensed temperature is above a desired set-back temperature set point regardless of whether the sensed humidity is above a desired set-back humidity set point whereby the controller ignores the sensed humidity and the desired set-back humidity set point when the sensed temperature is above the desired set-back temperature set point.
 2. The method of claim 1, further comprising the step of establishing by the controller, in the first mode, operation of the compressor at full capacity and operation of the blower at full capacity when the sensed temperature rises more than the predetermined amount above the desired temperature set point.
 3. The method of claim 1, wherein the set-back mode of operation comprises operating the air conditioner at a reduced level when the sensed humidity is below the desired set-back humidity set point and above a programmed humidity set point programmed for use in the first mode as the desired humidity set point and the sensed temperature is above the desired set-back temperature set point.
 4. The method of claim 3, wherein the desired set-back humidity set point for the set-back mode exceeds the programmed humidity set point programmed for use as the desired humidity set point in the first mode by at least a value of 15 percent relative humidity.
 5. The method of claim 3, wherein the desired set-back temperature set point for controlling operation of the air conditioner in the set-back mode of operation is at least 5 degrees higher than the programmed temperature set point programmed for use as the desired temperature set point in the first mode of operation.
 6. The method of claim 3, further comprising the step of establishing by the controller, in the set-back mode, operation of the compressor at full capacity and operation of the blower at full capacity when the sensed temperature rises more than a predetermined amount above the desired set-back temperature set point.
 7. The method of claim 1, further comprising the step of switching by the controller from the first mode of operation to the set-back mode of operation based on programmed time period settings selected by a user of the thermostat.
 8. The method of claim 1, further comprising the step of establishing by the controller in the set-back mode of operation, air conditioner operation with the blower and the compressor at a reduced capacity when the sensed humidity is above the desired set-back humidity set point and the sensed temperature is below the desired set-back temperature set point. 